Coil spring, and method for manufacturing coil spring

Abstract

A coil spring according to the present invention is formed by winding a wire material in a spiral, wherein a coating layer is provided on at least part of the surface of a portion of the wire material in which the gap between loops of the wire material is narrower than the wire diameter of the wire material, and the coating layer comprises a slip agent.

Description

Coil spring and manufacturing method of coil spring

[0001] The present invention relates to a coil spring and a method for manufacturing a coil spring.

[0002] Coil springs have been used as spring components in vehicle suspension systems and the like. Coil springs are generally formed by winding a wire rod having a circular cross section (see, for example, Patent Document 1). Furthermore, these coil springs are provided with a covering tube to suppress abnormal noises that occur when the wire rods come into contact with each other (inter-wire contact) when compressed by vibration, impact, or the like.

[0003] Coil springs are required to have abrasion resistance against wear caused by contact between the wires as well as to prevent abnormal noise caused by contact between the wires.

[0004] Japanese Patent Application Laid-Open No. 2003-206968

[0005] However, if the gap between the wires is narrow, it becomes difficult to cover the coil spring with the covering tube, resulting in a coil spring without the covering tube. In a coil spring without the covering tube, there is a risk of reduced wear resistance due to contact between the wires, etc.

[0006] The present invention has been made in view of the above, and aims to provide a coil spring and a method for manufacturing a coil spring that can ensure wear resistance even when there are portions where the gaps between the wire rods are narrow.

[0007] In order to solve the above-mentioned problems and achieve the object, the coil spring of the present invention is a coil spring formed by spirally winding a wire material, characterized in that a coating layer is provided on at least a part of the surface of the wire material in a portion where the gap between the wire material is narrower than the wire diameter of the wire material, and the coating layer contains a slip agent.

[0008] Furthermore, in the coil spring according to the present invention, in the above invention, a coating film is applied to the wire material, and the coating layer is provided on the coating film.

[0009] Furthermore, in the coil spring according to the present invention, the coating layer contains a rust inhibitor.

[0010] Furthermore, the method for manufacturing a coil spring according to the present invention is a method for manufacturing a coil spring formed by spirally winding wire material, and is characterized in that a coating layer is formed by applying a coating agent containing a slip agent to at least a portion of the surface of the wire material in a portion where the gap between the wire material is narrower than the wire diameter of the wire material.

[0011] In addition, the method for manufacturing a coil spring according to the present invention is characterized in that, in the above invention, the coating layer is formed by immersing the wire in the liquid coating agent.

[0012] In addition, the method for manufacturing a coil spring according to the present invention is characterized in that, in the above invention, the coating layer is formed by spraying the coating agent onto the wire.

[0013] Furthermore, the method for manufacturing a coil spring according to the present invention is characterized in that, in the above invention, the wire rod is coated with a paint film, and the coating layer is formed on the paint film.

[0014] Furthermore, the method for manufacturing a coil spring according to the present invention is characterized in that, in the above invention, the paint film is subjected to a surface treatment, and the coating layer is formed on the paint film that has been subjected to the surface treatment.

[0015] According to the present invention, it is possible to ensure wear resistance even when there are narrow gaps between wire rods.

[0016] Fig. 1 is a plan view showing the configuration of a coil spring according to an embodiment of the present invention. Fig. 2 is a diagram (part 1) for explaining an example of a method for forming a coating layer on a coil spring according to an embodiment of the present invention. Fig. 3 is a diagram (part 2) for explaining an example of a method for forming a coating layer on a coil spring according to an embodiment of the present invention.

[0017] Hereinafter, embodiments for carrying out the present invention (hereinafter referred to as "embodiments") will be described with reference to the accompanying drawings. Note that the drawings are schematic, and the relationship between the thickness and width of each part, the thickness ratio of each part, etc. may differ from the actual ones, and the drawings may also include parts with different dimensional relationships and ratios.

[0018] 1 is a plan view showing the configuration of a coil spring according to one embodiment of the present invention. The coil spring 1 is formed, for example, by spirally winding a wire made of spring steel around a predetermined axis. In this embodiment, an example will be described in which this predetermined axis coincides with the central axis N of the coil spring 1. The coil spring 1 is used, for example, as a suspension spring, an engine valve spring, a drive system component (clutch) spring, a tensioner spring, etc.

[0019] The coil spring 1 is formed by winding a wire in a spiral shape around a central axis N. The wire is formed using, for example, spring steel or other metal materials. Examples of other metal materials include materials made of a single metal or alloys. Alternatively, wire formed using resin or the like may be used. Note that the example shown in FIG. 1 illustrates a configuration in which the diameter (the diameter of the circle formed by the wire when viewed from the direction of the central axis N) due to the winding (winding) varies partially in the direction of the central axis N. However, this is not limiting and the diameter can be modified as appropriate. Also, while FIG. 1 illustrates an example in which the wire is wound around a linear center line (the central axis N), the coil spring may also be formed by winding the wire around a center line that is at least partially curved, for example.

[0020] The coil spring 1 has a pitch that corresponds to the distance between the central axes of the wire rods that varies partially along the direction of the central axis N. As a result, the gaps between the wire rods vary partially in the direction of the central axis N in the coil spring 1. The gaps between the wire rods correspond to the distance between the wire rods in the direction of the central axis N (gap distance Is (see FIG. 1)). For example, in the example shown in FIG. 1, the gap on the right side of FIG. 1 is smaller than the gap on the left side. The coil spring 1 has a first winding portion 11 and a second winding portion 12 that is continuous with the first winding portion 11. The gap distance of the second winding portion 12 is relatively narrower than the gap distance of the first winding portion 11.

[0021] Furthermore, in the coil spring 1, the gap distance Is of the second winding portion 12 is smaller than the wire diameter Rr of the wire material constituting the coil spring 1. Here, the wire diameter Rr corresponds to the diameter of the wire material cross section when the cross section of the wire material is circular in a cross section cut on a plane perpendicular to the longitudinal direction of the wire material. Note that, in the case where the cross section of the wire material is angular, for example, the length of one side forming the outer edge or the length of the diagonal in the cross section cut on a plane perpendicular to the longitudinal direction of the wire material corresponds to the wire diameter. In this specification, the length of the cross section of this angular wire material is described as corresponding to the "wire diameter." Note that, in this embodiment, the gap distance of the first winding portion 11 is described as being larger than the wire diameter Rr even in the narrowest gap.

[0022] A coating layer 12a is provided on the second winding portion 12. This coating layer 12a is formed on the outermost surface of the coil spring 1. The coating layer 12a is, for example, a film formed by a coating agent in which a slip agent is blended into a polymeric material or an inorganic material, that is, a polymeric film containing a slip agent or an inorganic film containing a slip agent.

[0023] The polymer material can be selected from thermoplastic resins, thermoplastic elastomers, thermosetting resins, thermosetting elastomers, and the like.

[0024] Examples of thermoplastic resins include various resins such as polyolefin resin, polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene resin, polyester resin, polyamide resin, polycarbonate resin, polyvinyl acetate resin, polyurethane resin, polytetrafluoroethylene resin, and polyacrylic resin.

[0025] Examples of the thermoplastic elastomer include various elastomers such as styrene-based thermoplastic elastomers, olefin-based thermoplastic elastomers, vinyl chloride-based thermoplastic elastomers, urethane-based thermoplastic elastomers, and amide-based thermoplastic elastomers.

[0026] Examples of the thermosetting resin include various resins such as phenolic resin, epoxy resin, melamine resin, urea resin, unsaturated polyester resin, alkyd resin, polyurethane, and thermosetting polyimide.

[0027] Examples of thermosetting elastomers include various resins such as isoprene rubber, butadiene rubber, styrene-butadiene rubber, acrylonitrile-butadiene rubber, chloroprene rubber, nitrile rubber, butyl rubber, ethylene propylene rubber, chlorosulfonated polyethylene, acrylic rubber, fluororubber, epichlorohydrin rubber, urethane rubber, and silicone rubber.

[0028] Examples of inorganic materials include ceramics, such as oxides such as aluminum oxide, magnesium oxide, zinc oxide, titanium oxide, and silicon oxide, nitrides such as boron nitride, aluminum nitride, and silicon nitride, carbides such as silicon carbide and boron carbide, and composites thereof.

[0029] Examples of slip agents include hydrocarbon compounds, hydroxy fatty acids or metal salts thereof, aliphatic alcohols, silicone compounds, and fluorine compounds.

[0030] Examples of hydrocarbon compounds include low molecular weight waxes, paraffin waxes, polyethylene waxes, and chlorinated hydrocarbons.

[0031] Examples of hydroxy fatty acids or metal salts thereof include higher fatty acids such as lauric acid, stearic acid, and behenic acid, hydroxystearic acid, and metal salts thereof (metal salts such as zinc salts).

[0032] Examples of the fatty alcohol include stearyl alcohol, lauryl alcohol, and palmityl alcohol.

[0033] Examples of silicone compounds include polydimethylsiloxane, polyether-modified polydimethylsiloxane, and polymethylalkylsiloxane.

[0034] Examples of fluorine-based compounds include polytetrafluoroethylene (PTFE); tetrafluoroethylene-perfluoroalkyl vinyl ether copolymers (PFA) such as tetrafluoroethylene-perfluoromethyl vinyl ether copolymer (MFA), tetrafluoroethylene-perfluoroethyl vinyl ether copolymer (EFA), and tetrafluoroethylene-perfluoropropyl vinyl ether copolymer.

[0035] The slip agent also includes inorganic fillers (calcium carbonate, talc, kaolin clay, silica, mica, calcium silicate, aluminum hydroxide, alumina, barium sulfate, titanium dioxide, zinc oxide, etc.).

[0036] Furthermore, a rust inhibitor or a material having wear resistance may be added to the slip agent. Examples of rust inhibitors include amine-based organic compounds, condensed aluminum phosphate, and fatty acid salts. Examples of amine-based organic compounds include nitrites, carbonates, and carboxylates of amines. In addition to the above materials, materials that function as lubricants or surfactants can also be used as slip agents. Furthermore, the slip agent may be contained in a molecularly dispersed state or in particulate form in the polymer material film or inorganic film.

[0037] Next, a method for forming the coating layer 12a in the second wound portion 12 will be described with reference to Figures 2 and 3. Examples of methods for forming the coating layer 12a include application methods such as dipping and spraying. Although the dipping and spraying methods will be described below, other known methods such as application using a brush or nozzle can also be used.

[0038] [Dipping Method] Figure 2 is a diagram illustrating an example of a method for forming a coating layer on a coil spring according to an embodiment of the present invention. In the dipping method, as shown in Figure 2, in a coil spring 100 having a first winding portion 111 in which the winding pattern of the wire corresponds to the first winding portion 11 and a second winding portion 112 in which the winding pattern of the wire corresponds to the second winding portion 12, the second winding portion 112 is placed in a container 200 containing the above-mentioned coating agent 201 and is held in the liquid for a predetermined time or is held in the liquid while being rocked. By this dipping, the coating agent adheres to the surface of the second winding portion 112, and the coating layer 12a is formed by drying and solidifying.

[0039] [Spray Method] Fig. 3 is a diagram for explaining an example of a method for forming a coating layer on a coil spring according to an embodiment of the present invention. In the spray method, as shown in Fig. 3, a spray 300 is used to spray the above-mentioned coating agent 301 in a mist form onto the second winding portion 112. This spraying causes the coating agent to adhere to the surface of the second winding portion 112, and the coating layer 12a is formed by drying and solidifying.

[0040] In the embodiment of the present invention described above, the coating layer 12a is formed in the portion where the gap distance is narrower than the wire diameter (wire diameter Rr), thereby suppressing wear when the wires come into contact with each other. According to this embodiment, the formation of this coating layer 12a makes it possible to ensure wear resistance even when the coil spring has a portion where the gap between the wires is narrow.

[0041] (Modification) Next, a modification of the embodiment of the present invention will be described. In this modification, the coil spring will be described as having a wire material coated with a coating film to impart corrosion resistance. Below, differences from the embodiment will be described, and the same components will be assigned the same reference numerals and will not be described again.

[0042] In this modification, a coating is applied to the surface of the wire material that constitutes the coil spring 1. This coating is applied to improve the corrosion resistance of the wire material and covers the entire wire material. Examples of materials for the coating include known corrosion-resistant materials such as polyurethane resin and acrylic resin. The coating is applied by a known coating method such as powder coating.

[0043] In this modification, the coil spring 1 is produced by forming a coating layer 12a on the second winding portion 112 of the coil spring 100 (see, for example, FIG. 2 ) to which the above-described coating film has been applied. That is, the coating layer 12a is provided on the coating film. At this time, in order to strengthen the adhesion of the coating layer 12a to the wire, it is preferable to subject the second winding portion 112 to a surface treatment before forming the coating layer 12a. As the surface treatment, known treatments such as plasma treatment, blast treatment, primer treatment, corona treatment, and flame treatment can be used.

[0044] In the surface treatment according to the modified example, a surface treatment is performed on the second winding portion 112 of the coil spring 100. For example, by plasma treatment, fine irregularities are formed on the surface (coating surface) of the second winding portion 112, which can increase the adhesive strength of the coating layer 12 a.

[0045] In the present modified example described above, similar to the above-described embodiment, a coating layer 12a is formed in the portion where the gap distance is narrower than the wire diameter (wire diameter Rr), thereby suppressing wear when the wires come into contact with each other. According to this modified example, by forming this coating layer 12a, it is possible to ensure wear resistance even when the coil spring has a portion where the gap between the wires is narrow.

[0046] In this modification, the coating layer 12a is applied to the coil spring 100 in which a coating film is applied to the wire material, thereby ensuring the corrosion resistance of the wire material and imparting wear resistance to the wire material. Furthermore, according to this modification, the adhesion of the coating layer 12a to the wire material (coating film) can be further strengthened by performing a surface treatment on the coating film.

[0047] Up to this point, we have described embodiments for carrying out the present invention, but the present invention should not be limited to the above-described embodiments. In the above-described embodiments, an example has been described in which a coating is applied to the entire surface of the second winding portion 12. However, it is sufficient that the coating layer 12a is applied at least to positions where the wire rods may come into contact with each other due to deformation of the coil spring 1. For example, the coating layer 12a may be formed on the portions of the second winding portion 12 where the wire rods face each other in the direction of the central axis N. Furthermore, if the gap distance between the wire rods in the coil spring varies partially and there are intermittent narrow gaps, the coating layer is also formed intermittently to match those gaps.

[0048] As such, the present invention may include various embodiments not described here, and various design changes may be made within the scope of the technical idea specified by the claims.

[0049] In addition to the coil springs described in the above-described embodiments, the coating layer of the present invention can also be applied to, for example, a laminated leaf spring composed of multiple stacked leaf springs. When a load is applied to a laminated leaf spring from the stacking direction (thickness direction of the leaf springs), the leaf springs may flex and deform, causing the end regions of the leaf springs to come into contact and generate abnormal noise. To address this issue, a sound-absorbing component called a silencer may be pre-installed in the end regions of the leaf springs. However, if the silencer falls off or becomes detached from the leaf springs, the end regions of the leaf springs may come into contact with each other, generating abnormal noise and possibly causing the paint on the contacting areas to wear away. For such laminated leaf springs, instead of providing a silencer, the coating layer of the present invention can be applied to at least a portion of the end regions where the leaf springs may come into contact during operation, thereby improving wear resistance. This improves the durability of the laminated leaf spring.

[0050] As described above, the coil spring and the method for manufacturing the coil spring according to the present invention are suitable for ensuring wear resistance even when there are portions where the gaps between the wire rods are narrow.

[0051] 1, 100 Coil spring 11, 111 First winding portion 12, 112 Second winding portion 12a Coating layer

Claims

1. A coil spring formed by helically winding a wire, wherein a coating layer is provided on at least a portion of the surface of the wire in a portion where the gap between the wires is narrower than the wire diameter of the wire, and wherein the coating layer contains a slip agent.

2. The coil spring according to claim 1, characterized in that a paint film is applied to the wire material, and the coating layer is provided on the paint film.

3. The coil spring according to claim 1 or 2, characterized in that the coating layer contains a rust inhibitor.

4. A method for manufacturing a coil spring formed by spirally winding a wire, comprising the steps of: applying a coating agent containing a slip agent to at least a portion of the surface of the wire in a portion where the gap between the wires is narrower than the wire diameter of the wire, thereby forming a coating layer.

5. The method for manufacturing a coil spring according to claim 4, characterized in that the coating layer is formed by immersing the wire in a liquid coating agent.

6. The method for manufacturing a coil spring according to claim 4, characterized in that the coating layer is formed by spraying the coating agent onto the wire.

7. The method for manufacturing a coil spring according to claim 4, characterized in that a coating film is applied to the wire material, and the coating layer is formed on the coating film.

8. The method for manufacturing a coil spring according to claim 7, further comprising the steps of: subjecting the paint film to a surface treatment; and forming the coating layer on the paint film that has been surface-treated.

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